Solvent refining of mineral oil



Patented July 28, 1936 SOLVENT REFINING 0F MINERAL OIL Francis X. Govers, Vincennes, Ind, assignor to Indian Refining Company, Lawrenceville, 111., a corporation of Maine No Drawing. Application May 14, 1934, Serial No. 725,655

11 Claims.

This invention relates to the manufacture of mineral lubricating oils and more particularly to the manufacture of high viscosity index, low pour test lubricating oils from wax-bearing mineral oils.

This application is a continuation-in-part of my co-pending application Serial No. 715,300, filed March 13, 1934.

In its broadest aspect, the invention contemplates an improved process of treating hydrocarbon oils, particularly parafiin-bearing lubrieating fractions of petroleum with solvents to produce therefrom low pour test lubricating oils characterized by having a desired viscosity temperature relationship and improved lubricating qualities. The invention contemplates a process of manufacturing lubricating oils having low pour and cloud tests, low sulphur content, low Conradson carbon content, relatively high viscosity index and freedom from bodies of little or no lubricating value.

Lubricating oils of high viscosity index are characterized by having a relatively narrow increase in viscosity with respect to temperature. Such oils have the property of possessing the desired viscosity at elevated temperature with not too great a loss of mobility at very low temperature. The viscosity index of a given oil is readily determined by resorting to the method of Dean and Davis, published on pages 6184319 of the 1929 issue of Chemical and Metallurgical Engineering.

More specifically the invention comprises separating low viscosity index constituents and paralfin wax from wax-bearing mineral oil by treatment with aniline in the presence of a modifying solvent selected from the aliphatic alcohols of the amyl group such as obtained from the chlorination of propane and from fusel oil.

My invention contemplates a process wherein these constituents are removed from the oil by extraction with aniline in the presence of a mix ture of amyl alcohols having a boiling point of 240 F. and above, and particularly a commercial mixture of amyl alcohol having a boiling range of from 241 F. to about 277 F. It is contemplated that the wax-bearing oil may be subjected to an initial separating treatment to remove hydrocarbon material which, acting as a third component of a dewaxing mixture, will tend to modify the wax anti-solvent properties of the solvent mixture. Thereafter, the preliminarily extracted oil may be dewaxed, following which the dewaxed oil may be subjected to a further fractional separation into fractions respectively rich in relatively low and relatively high viscosity index constituents.

In accordance with the procedure of my invention, wax-bearing oil may be mixed with a mixture composed of about three parts of aniline and two parts of an amyl alcohol mixture, such as described above or Pentasol, using about two parts of this' solvent mixture to one part of oil. The resulting mixture separates into two layers at temperatures of around 95 F., the lower layer comprising highly naphthenic oil while the upper layer comprises relatively more paraifinic oil including paraffin wax.

After removal of the bottom or naphthenic layer, additional quantities of aniline and amyl alcohol mixture are added to the remaining layer suflicient to form a solvent mixture composed of about three parts of aniline and seven parts of amyl alcohol mixture, and in the proportion of about four parts of. solvent mixture to one part of oil. This mixture contains the solvents in proportions such that the mixture exerts a selective action as between wax and oil at temperatures of 0 F. and below.

This mixture is then chilled to below 0 F. in order to solidify the wax which may then be removed by filtering or centrifuging.

The dewaxed mixture may then be subjected to further separation, and which is advantageously effected by heating and distilling ofi a portion, or substantially all, of the amyl alcohol mixture, leaving a mixture of oil and solvent comprising mainly aniline and which, when cooled, will separate into layers respectively rich in relatively low and relatively high viscosity index constituents. due to the selective action of the aniline.

It may be desirable, in the case of certain oils, to reverse the foregoing order of steps, and subject the oil to solvent separation to remove all of the undesired low viscosity index constituents, and thereafter dewaxing the thus separated oil to produce the final desired product of low pour test. In other cases, it may be sufficient to subject the oil to dewaxing first, followed by separation into the desired fractions.

As a specific example of the practice of my invention, I may take an acid-treated wax distillate derived from Mid-Continent crude and having the following characteristics:

Gravity "A. P. I 22.3 Saybolt universal viscosity at 210 F Pour test F One thousand gallons of this oil is mixed with 800 gallons of amyl alcohol mixture. To this is added 1,200 gallons of aniline and the mixture well stirred to effect complete solution. The mixture is then brought to a temperature of about F. and allowed to separate into two layers.

The bottom layer, composed of naphthenic material and comprising approximately 750 gallons of mixed solvent liquid and 250 gallons of dissolved oil, is then withdrawn.

To the upper layer, comprising approximately 250 gallons of solvent liquid and 750 gallons of wax and oil, is added 750 gallons of aniline and 2,000 gallons of amyl alcohol mixture. This mixture is well stirred and chilled to about -20 F. and while maintained at that temperature is introduced to filtering means wherein the solid hydrocarbons are separated in the form of a filter cake.

The filter cake is washed with additional solvent liquid mixture of substantially the same composition and which has been chilled to a temperature of 20 F. This washed filtrate is used fora part of the solvent mixture in a succeeding batch, allowance being made for the oil contained therein.

From the dewaxed filtrate, substantially all of the amyl alcohol mixture is distilled and recovered. The resulting mixture is cooled to a temperature of approximately F. whereupon separation into two layers will occur. The upper layer will comprise the high viscosity index constituents, while the lower layer will contain the low viscosity index constituents. The resulting layers are separately removed and the solvent recovered therefrom.

The oil contained in the high viscosity index upper layer, after being finished by contact filtration in the presence of steam and clay, has the following characteristics:

Gravity A. P. I 28.6 Saybolt universal viscosity at 210 F 67 Viscosity index 9'! Pour test F 10 In the event extremely high viscosity index oils are desired, approaching the order of 100 viscosity index, it may be advantageous to further extract the high viscosity index upper layer obtained in the foregoing final separation. In this case, this high viscosity index layer may be further extracted, either by batch or countercurrent treatment with aniline or the desired proportions of aniline and amyl alcohol mixture. An example of oil obtained by such further extraction, will have the following characteristics:

Gravity A. P. I 30.4 Salbolt universal viscosity at 210 F 65 Viscosity index 100 Four test F -15 Percent carbon residue Percent sulphur other hand, in extracting the oil to efiect separation into fractions of differing viscosity indices, the proportion of aniline may vary from 40% to 90%, depending upon the temperature at which the extraction is carried out.

The presence of amyl alcohol mixture in the separating mix possesses the advantage of rendering the mixture of solvent and oil more susceptible to the selective action of the aniline. It also serves to reduce the viscosity of the mixture to thereby facilitate not only better contact between solvent and constituents of the oil but permit more ready separation into the resulting layers.

The invention is not limited to the production of final products of the characteristics of those produced in the examples given above. Products of varying characteristics may be produced by varying the proportions of solvent liquids and n fractions, precipitates or' materials somewhat,

similar in nature derived in various ways from mineral oils.

Thus my invention is applicable to the treatment of hydrogenation products resulting from the hydrogenation of carbonaceous materials, or

mineral oils including liquid or solid hydrocarbon fractions derived from mineral oils. Hydrogenation products may contain substantial quantities of waxy or parafiin material as well as other constituents of relatively low lubricating value.

By treating such productsin accordance with my invention, final products of desired characteristics can be obtained.

The invention is not restricted to any particular operating condition such as that of temperature, or the composition of the solvent mixtures employed since these conditions may advantageously be varied, depending upon the nature of the fraction undergoing treatment as well as upon the particular characteristics desired in the final product.

It is also contemplated, in many instances, that it may be of advantage to carry on the filtration step in the presence of a comminuted solid filter aid material. Such material may be admixed with the chilled mixture of oil and solvent liquid prior to introduction to the filtering means.

In the treatment of residual oils or of certain distillate oils which may contain asphalt, it may be desirable to separate the asphalt prior to the treatment for the extraction of the naphthenic constituents or prior to the dewaxing step.

The separation of the asphalt may be carried out effectively by thoroughly mixing the oil with three to four volumes of amyl alcohol at temperatures of about F. After removal of the' asphaltic matter which separates from the diluted mass, aniline may be added in the desired proportion to effect solvent extraction of the naphthenic constituents, as heretofore described. If desired, a portion of the amyl alcohol contained in the oil after separation of the asphalt may be removed in order to secure the desired ratio of aniline to amyl alcohol and of total sol-- vent to the oil undergoing treatment. Obvious- 1y, other proportions of amyl alcohol and various temperatures may be employed in the asphalt 75.

separation step, those'recited above-beinggiven merely for the purpose of illustration.

By operating in accordance with this method,

the amyl alcohol may be carried throughout the processing operations of asphalt separation, ex-

traction of naphthenic constituents and dewaxing without incurring the expense of stripping this solvent from the oil.

While a mixture of amyl alcohols having a boiling range of from 241 to 277 F. and obtained from the chlorination of pentane has been referred to in the example given above, it is contemplated that amyl alcohol produced by fermentation, as in the case of the fusel oil of commerce, may also be employed.

Obviously many modifications and variations of the invention, as hereinbeiore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

i I claim: a

1. The process of manufacturing high viscosity index lubricating oil having a low pour test and low'in residual carbon-forming bodies from a residual type of wax-bearing mineral oil containing asphaltic constituents which comprises mixing the oil with a commercial amyl alcohol mixture of about 241 to 277 F. boiling temperature in sufficient amount to precipitate asphaltic constituents from the oil, removing the precipi tated asphaltic constituents, mixing with the remaining solution of oil and alcohol aniline in such proportion that at temperatures of F. and below the solvent mixture has substantially complete solvent action on the liquid constituents but substantially no solvent action on the solid wax constituents of the oil, chilling the mixture to precipitate wax constituents of the oil, removing the wax thus precipitated, removing from the resulting dewaxed mixture a portion of the amyl alcohol to thereby alter the selective action of the solvent mixture, separating from the remaining mixture a fraction of desired viscosity index and low pour test, and removing the solvent therefrom.

2. The process of manufacturing high viscosity index lubricating oil having a low pour test and low in residual carbon-forming bodies from a residual type of wax-bearing mineral oil containing asphaltic constituents which comprises mixing the oil with a commercial amyl alcohol mixture of about 241 to 277 F. boiling temperature in sufiicient amount to precipitate asphaltic constituents from the oil, removing the precipitated asphaltic constituents, mixing with the remaining solution of oil and alcohol aniline in proportion with the mixture of oil and alcohol such that the mixture has a selective solvent action as between wax and oil at temperatures of the order of -20 F., chilling the mixture to solidify the wax, removing the wax thus solidified, and recovering the solvent liquid from the dewaxed oil.

3. The process of manufacturing high viscosity index lubricating oil having a low pour test and low in residual carbon-forming bodies from a residual type of wax-bearing mineral oil containing asphaltic constituents which comprises mixing the oil with a commercial amyl alcohol mixture of about 241 to 277 F. boiling temperature in suflicient amount to precipitate asphaltic constituents from the oil, removing the precipitated asphaltic constituents, mixing aniline with the remaining solution of oil and alcohol in such proportion that the aniline comprises from about 20% to about 35% of 'the mixture, chilling the mixture to solidify the wax, removing the wax thussolidified, and recovering the solvent liquid from the dewaxed oil.

4. The process of manufacturing high viscosity index lubricating oil low in residual carbonformin'g bodies from a residual type mineral oil containing asphaltic constituents which comprises mixing the oil with a commercial amyl alcohol mixture of about 241 to 277 F. boiling temperature in sufficient amount to precipitate asphaltic constituents from the oil, removing the precipitated asphaltic constituents, mixing aniline with the remaining mixture in proportion such that the aniline comprises from about40% to 90 %'of the mixture, separating the mixture into extract and raffinate phases, separating the raiiinate phase, and recovering the solvent liquid therefrom.

-5. The process of manufacturing high viscosity index'lubricating'oil having a low pour test and low in residual carbon-forming bodies from a residual type of wax-bearing mineral oil containing asphaltic constituents which comprises mixing the -oil with a commercial amyl alcohol mixture of about 241 to 277 F. boiling temperature in sufiicientamount to precipitate asphaltic constituents from the oil, removing the precipitated asphaltic constituents, mixing aniline with the remaining mixture of oil and alcohol forming an extract and a rafiinate phase containing wax constituents, removing the extract phase, adding furthersolvent liquids to said raflinate phase to form a mixture therewith containing aniline and said alcohol in proportions such that the solvent mixture has selective action as be with the oil a solvent liquid mixture composed of substantial proportions of aniline and amyl alco- 'hol of about 241 to 277 F. boiling temperature in proportions such that at temperatures of 0 F. and below the solvent mixture has substantially complete solvent action on the liquid constituents but substantially no solvent action on the solid wax constituents of the oil, chilling the mixture to precipitate wax constituents of the oil, removing the wax thus precipitated, removing from the resulting dewaxed mixture a portion of the amyl alcohol to thereby alter the selective action of the solvent mixture, separating from the remaining mixture a fraction of desired viscosity index and low pour test, and removing the solvent therefrom.

7. The process of dewaxing mineral lubricating oil comprising dissolving the oil in a solvent mixture composed of aniline and amyl alcohol of about 241 to 277 F. boiling temperature mixed in proportion with each other and to the oil such that the mixture has a selective solvent action as between wax and oil at temperatures of the order of F., chilling the mixture to solidify the wax, removing the wax thus solidified, and recovering the solvent liquid from the dewaxed oil.

8. The process of dewaxing mineral lubricating oil comprising dissolving the oil in a solvent mixture composed of aniline and amyl alcohol of about 241 to 277 F. boiling temperature in which the aniline comprises from about.20% to about of the mixture, chilling ,the mixture to.

solidify the wax, removing the wax thus solidified. and recovering the solvent liquid from the dewaxed oil.

9. The method of separating mineral oil containing relatively high viscosity index and relatively low viscosity index oil into fractions respectively rich in relatively high and relatively low viscosity index constituents comprising extracting the oil with a solvent mixture composed of aniline and amyl alcohol of about 241 to 277 F. boiling temperature, the aniline comprising from about to about of the mixture, whereby the mixture of solvent and oil separates into two in proportions such that the solvent mixture has selective action as between wax and oil at temperatures of 0 F. and below, chilling the mixture to separate the wax, removing the wax thus separated, removing amyl alcoholfrom the dewaxed 5 mixture in such proportions that the remaining solvent mixture exerts selective action as between difiering viscosity index constituents of the dewaxed oil, and the mixture of oil and remaining solvent separates into layers, separately removl0 .ing the layers, and recovering the solvent liquids therefrom.

11. The method of manufacturing low pour test, high viscosity index oil from wax-bearing mineral lubricating oil wherein the oil is dewaxed l5 and then extracted, comprising mixing with the oil aniline and amyl alcohol of about 241 to 277 F. boiling temperature in proportions such that the solvent mixture exerts a selective action as between wax and oil at temperatures of the order 20 of 20 F., chilling the mixture to separate the wax, removing the wax thus separated, removing substantially all of the amyl alcohol from the dewaxed solvent mixture, thereby producing a mixture of dewaxed oil and solvent liquid comprising 25 mainly aniline having a selective action as between differing viscosity index constituents of the dewaxed oil, separating from said mixture a fraction of desired viscosity index and low pour test, and removing the solvent therefrom. 30

FRANCIS X. GOVERS. 

